2015291201547965108320565564D3106287F2BFFF1FF975A7AC3B856C6-048C-4CB5-953D-83749537B9B2121020141212015Tomáš LacknerThis is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Abstract

The genus Exaesiopus Reichardt, 1926 is revised herein. It now contains seven species; one new combination is proposed: Pachylopusglaucus = Exaesiopusglaucus (Bickhardt, 1914), comb. n., and one species is described as new: Exaesiopustherondisp. n. from Afghanistan. Subspecies Exaesiopusgrossipesberberus Peyerimhoff, 1936 is sunk in synonymy with Exaesiopusgrossipes (Marseul, 1855), syn. n. Lectotypes and paralectotypes, respectively, for Saprinusgrossipes Marseul, 1855, Exaesiopusgrossipesberberus Peyerimhoff, 1936 and a neotype for Pachylopusglaucus Bickhardt, 1914 are designated. Exaesiopusgrossipes is re-described; other species are provided with diagnostic descriptions and supplemented by SEM micrographs, colour images, and line drawings of their male genitalia. A key to species is given. Exaesiopusglaucus (Bickhardt, 1914) is newly recorded from the Republic of South Africa; Exaesiopustorvus Reichardt, 1926 is new to Uzbekistan and Russia; Exaesiopusatrovirens Reichardt, 1926 is new to Ukraine and Tajikistan; and Exaesiopushenoni (Schmidt, 1896) is new to Libya and Djibouti.

The genus Exaesiopus was erected by Reichardt (1926) based on the species Saprinusgrossipes Marseul, 1855. Reichardt (1926) mainly used the presence of prosternal vestiture as the discriminating character from the presumably closely related genus Hypocaccus C. Thomson, 1867. In the same paper he described two further species from ex-Soviet Middle Asia, Exaesiopustorvus and Exaesiopusatrovirens, and combined the species Pachylopushenoni Schmidt, 1896 into Exaesiopus. Peyerimhoff (1936), based on the elytral punctation, split the species Exaesiopusgrossipes into two subspecies: Exaesiopusgrossipesgrossipes from the northern shore of the Mediterranean Sea and South Europe, and Exaesiopusgrossipesberberus from North Africa (Algeria, Tunisia). Thérond (1964) added an additional species, Exaesiopuslaevis from Somalia, to the genus. Lackner (2010) included a diagnosis and a brief discussion of the monophyly of Exaesiopus in his Review of the Palaearctic Genera of Saprininae (Histeridae), without having examined the Somali species. In the discussion pertaining to Exaesiopus I mentioned that the genus is most likely non-monophyletic and its relationship to the genus Hypocaccus should be the focus of future studies. The single synapomorphy of Old World Exaesiopus (ciliate pronotal hypomeron) is prone to parallelism and shared with at least two Nearctic species of Hypocaccus. The present revision of the genus is therefore meant to act chiefly as a tool for identifying Hypocaccus-like Saprininae species with ciliate pleura and sterna from the Old World. These are grouped here under the currently valid genus Exaesiopus; however, a worldwide review and phylogenetic study of all Hypocaccus-like taxa is a prerequisite for a sound classification of this difficult group of beetles. During the years 2009–2014 I have had the opportunity to examine many rare Saprininae taxa, including Exaesiopuslaevis from Somalia and Hypocaccus (Hypocaccus) glaucus (Bickhardt) from Namibia. The results of these examinations are presented below. This work presents another contribution to on-going revisionary work on the genera of the subfamily Saprininae (Lackner 2009a, b, c, 2010, 2011a, b; Lackner 2012; Lackner 2013a, b; Lackner and Gomy 2013; Lackner 2014a, b, c, d; Lackner and Tishechkin 2014; Tishechkin and Lackner 2012).

Material and methods

All dry-mounted specimens were relaxed in warm water for several hours or overnight, depending on the body size. After removal from their original cards, the beetles were side-mounted on triangular points and observed under a Nikon 102 stereoscopic microscope with diffused light. Some structures were studied using methods described by Ôhara (1994): the head and male genitalia were macerated in a hot 10% KOH solution for about 15 minutes, cleared in 80% alcohol, macerated in lactic acid with fuchsine, incubated at 60 °C for two hours, and subsequently transferred into a mixture of glacial acetic acid 1 part and methyl salicylate 1 part heated at 60 °C for 15 minutes and cleared in xylene. Specimens were then observed in α-terpineol in a small glass dish. Digital photographs of the male terminalia, mouthparts and antenna were taken by a Nikon 4500 Coolpix camera and edited in Adobe Photoshop CS4. Based on the photographs or direct observations, the genitalia were drawn using a light-box Hakuba klv-7000. SEM photographs were taken with a JSM 6301F microscope at the laboratory of Faculty of Agriculture, Hokkaido University, Sapporo, Japan as well as at the Laboratory of the Electron Microscopy at the Faculty of Biology, Charles University, Prague, Czech Republic. Colour images were produced by F. Slamka (Bratislava, Slovakia). All available specimens were measured with an ocular micrometre. Beetle terminology follows that of Ôhara (1994) and Lackner (2010). Separate lines of the same label are demarcated by a slash (/). The following acronyms of museums and private collections are used throughout the text:

Although the genus has been recently diagnosed (Lackner 2010: 111), it requires modification to accommodate the newly examined species Exaesiopuslaevis, the newly included Exaesiopusglaucus (Bickhardt), and the newly described Exaesiopustherondi. Body in most species strongly convex, especially dorsally; cuticle light to dark brown to almost black, in several species with (feeble) green lustre. Clypeus anteriorly elevated (Fig. 4); frontal stria carinate (Fig. 2); frons with several chevrons, occasionally surrounded by numerous tiny rugae (Fig. 2); pronotal hypomeron setose (Fig. 55). Elytra in most species with punctation; in all species striate; pleura and sterna furnished with short setae (Fig. 41). Prosternum with both sets of striae complete, and occasionally with weakly impressed prosternal foveae (Fig. 6). Protibia with 2–3 (large) teeth topped by triangular denticle; protibial spur in most species inconspicuous (apparently absent); metafemora thickened; metatibiae triangularly dilated and thickened (except for Exaesiopusglaucus).

Differential diagnosis.

Members of Exaesiopus are generally morphologically most similar to the Old World species of the genus Hypocaccus, differing from them chiefly by the setose pronotal hypomeron, strongly convex body, thickened metafemora and triangularly dilated and thickened metatibiae. In North America, however, there are at least two species of Hypocaccus (Hypocaccuspropensus (Casey, 1893) and Hypocaccusservilis Casey, 1893) that are characterized by the presence of hypomeral setae.

Biology.

Exaesiopus species are almost exclusively found in sandy soils, beach dunes, river sands, and are also found in sandy areas further inland (e.g. Sahara desert). Morphologically they are well adapted to their fossorial habits. Species are often collected on rotting biological matter, e.g. under faeces, dead fish etc., and are occasionally found under coastal wrack or by shore washing. The middle Asian Exaesiopusatrovirens and Exaesiopustorvus are sometimes found burrowing under Tamarix. The biology of Exaesiopuslaevis and Exaesiopustherondi is unknown, the latter has been found inside the stomach of Kentish plover (Charadriusalexandrinus L. (Aves)).

Distribution.

Genus Exaesiopus has a generally circum-Mediterranean-Caspian-Turanian distribution, most westerly occurring on the Canary Islands, reaching Afghanistan in the east. Its members have also been collected in the Sahara desert (Laghouat, Algeria), reaching as far east as northern Somalia (Exaesiopuslaevis) or Djibouti (Exaesiopushenoni). Exaesiopusglaucus is known only from the Republic of South Africa and Namibia.

Peyerimhoff (1936: 227) distinguished the subspecies Exaesiopusgrossipesberberus from the nominotypical one based on elytral punctation that should cover almost the entire elytral disc basally and laterally up to the second dorsal elytral stria. Among the three specimens that he furnished with type labels, however, only the female from Laghouat (Algeria) exhibits these characteristics; the two males from Bône [=Annaba, Algeria] have their apical half (approximately) impunctate and the punctation of their elytral discs terminates in third elytral stria. Therefore, a female from Laghouat has been selected for the Lectotype. Peyerimhoff (1936: 227) himself did not specify which specimen(s) belonged to the type series; he listed several localities with his extremely brief diagnosis of the new subspecies. Both Laghouat and Bône [=Annaba] were among the listed localities.

Although this species has been recently re-described by the author (Lackner 2010: 112–116), I prefer to repeat this re-description here for the reason that the following species are morphologically rather similar to Exaesiopusgrossipes. Those species are consequently provided only with diagnostic descriptions outlining their respective differences.

Antennal scape with few short setae; club (Fig. 2) round, entire surface with thick short yellow sensilla intermingled with sparse slightly longer setae; sensory structures of the antennal club (Fig. 14) in form of stipe-shaped vesicle situated under circular sensory area on internal distal margin of the ventral side of antennal club.

Mesoventral disc (Fig. 7) somewhat convex, almost smooth, slightly wider than long; meso-metaventral sutural stria well impressed, with several accompanying punctures; intercoxal disc of metaventrite with longitudinal depression in male, smooth, basally with irregular sparse shallow fine punctures; lateral metaventral stria (Fig. 8) well impressed, carinate, obliquely arcuate, apically almost reaching metacoxa; lateral disc of metaventrite concave, with shallow setiferous punctures of various sizes, separated by approximately their own diameter; metepisternum with even denser and coarser punctation and setae, on apical third + metepimeron punctation much finer and sparser; metepisternal stria deeply impressed, present on metepimeron and approximately apical third of metepisternum.

Intercoxal disc of first abdominal sternite almost completely striate laterally; disc almost smooth, with sparse punctures along apical margin; lateral portion of disc of all visible abdominal sternites with short setae.

Exaesiopusgrossipes differs from the three species Exaesiopushenoni, Exaesiopustherondi and Exaesiopuslaevis chiefly by the shape of its protibia, which is on its outer margin furnished with three low teeth topped by triangular or rounded denticles (Figs 9, 10), whereas the three other mentioned species have their protibia furnished with two large teeth topped by triangular denticles on outer margin (Figs 61, 79 & 114). From Exaesiopusatrovirens and Exaesiopusglaucus it differs chiefly by the absence of a green metallic hue of the dorsum (compare Figs 1 with 73 & 98); from Exaesiopusglaucus it differs furthermore by thickened and dilated metatibia (compare Figs 13 with 106). On the other hand, some specimens of Exaesiopusgrossipes (especially from N. Africa that formerly belonged to the subspecies berberus) can resemble the specimens of Middle-Asian Exaesiopustorvus by their densely punctate dorsum. These specimens differ, however, from Exaesiopustorvus by their respective male genitalia (compare Figs 17–34 with 64–72) and the less punctate pronotal disc (see also Key to the species for details, below). Most specimens of Exaesiopusgrossipes, however (especially those from the northern shore of the Mediterranean Sea and South Europe) have distinctly less punctate dorsum than the specimens of Exaesiopustorvus.

This species is found on the beach under coastal wrack as well as further away from the waterfront, almost exclusively on sandy soil. Beetles can be found under rotting fish, excrements or buried under vegetation.

A variable species, covering vast area from the Canary Islands in the west to Iraq in the east. Its external morphology as well as male genitalia exhibit a certain degree of variation (compare Figs 17–25 and 26–34), but I find it difficult to discern discrete states among the variation and prefer to lump all examined specimens under the same species.

Body length: PEL: 2.50–2.75 mm; APW: 0.875–1.00 mm; PPW: 1.875–2.00 mm; EW: 2.125–2.20 mm; EL: 1.625–1.80 mm. Body (Fig. 35) similar to Exaesiopusgrossipes, but without any trace of metallic tinge; antennae similar to those of Exaesiopusgrossipes; sensory structures of the antennal club not examined. Mouthparts generally similar to those of Exaesiopusgrossipes; mentum (Fig. 36) sub-quadrate, feebly inwardly arcuate on anterior margin; anterior margin with several long setae, lateral margins with single row of sparse shorter ramose setae; stipes of maxilla with four setae (three in Exaesiopusgrossipes); rest of the mouthparts as in Exaesiopusgrossipes. Clypeus (Fig. 37) as in Exaesiopusgrossipes, almost smooth; frontal and supraorbital striae as in Exaesiopusgrossipes; postorbital stria missing (present in Exaesiopusgrossipes); frons with two deep chevrons.

Pronotal disc (Fig. 35) with ellipsoid to round, rather sparse punctation, punctures separated by their own to several times their diameters, postero-median part of disc always smooth, punctation stopping short of lateral pronotal margin leaving a narrow impunctate band; rest of the pronotum as in Exaesiopusgrossipes. Elytra generally as in Exaesiopusgrossipes; inner subhumeral stria shortly present medially; dorsal elytral striae for short distance surpassing elytral half; elytral punctation variable, in most specimens present only on fourth elytral interval, but can also at times be present on other elytral intervals (a specimen from Libya), or almost completely missing (a specimen from Algeria); along elytral suture can reach almost elytral base, punctures irregular, variously deep, separated often by several times their own diameter, elytral flanks and humeri always smooth. Propygidium (Fig. 38) and pygidium similar to those of Exaesiopusgrossipes; punctation somewhat sparser (compare Figs 5 and 38). Prosternum (Fig. 39) generally similar to that of Exaesiopusgrossipes, but prosternal foveae very weakly impressed, often indiscernible (absent?); prosternal process deeply concave, constricted, prosternal structures and configuration of the two sets of prosternal striae similar to those of Exaesiopusgrossipes. Disc of mesoventrite (Fig. 40) almost smooth, similar to that of Exaesiopusgrossipes, but almost as long as wide; meso-metaventral sutural stria undulate; intercoxal disc of metaventrite with longitudinal depression in both sexes, more prominent in male, smooth, basally with several irregular rows of sparse punctures; lateral metaventral stria (Fig. 41) obliquely arcuate, apically almost reaching metacoxa; lateral disc of metaventrite (Fig. 41) and metepisternum generally similar to those of Exaesiopusgrossipes, but metepisternum with denser and coarser punctation and longer setae; meterpisternal stria unrecognizable beneath setae (absent?). Intercoxal disc of first abdominal sternite as in Exaesiopusgrossipes. Protibia (Figs 42–43) on outer margin with a single massive triangular tooth, followed by another lower tooth; both teeth topped by triangular denticle followed by two-three inconspicuous rounded denticles entombed in outer protibial margin; protibial spur inconspicuous (absent?); outer part of posterior surface of protibia (Fig. 43) smooth, separated from comparatively narrower median part by a definite ridge, posterior protibial stria complete, terminating in two minuscule inner posterior denticles; inner margin of protibia with double row of long dense lamellate setae. Mesotibia (Fig. 44) as in Exaesiopusgrossipes, but denticles on outer margin longer. Metatibia (Fig. 45) even more triangularly dilated and thickened than that of Exaesiopusgrossipes; outer margin with about four strong denticles larger in size apically; dilated anterior margin dorsally with several irregular rows of scattered tiny rounded denticles.

Exaesiopushenoni is most similar to the species Exaesiopuslaevis and Exaesiopustherondi, with which it shares the shape of protibia (see also Key to species for details). From Exaesiopustherondi it differs by sparsely punctate pronotum, frons that is devoid of tiny irregular rugae, and anterior face of protibia, which is glabrous in Exaesiopushenoni, whereas it is obscurely variolate in Exaesiopustherondi. From Exaesiopuslaevis it differs by punctate body (almost impunctate in Exaesiopuslaevis) and present inner subhumeral stria (absent from Exaesiopuslaevis). From the remaining species of the genus Exaesiopushenoni differs by the shape of the protibia (see also Key to species for details).

Biology.

A typical psammophile, found in sand.

Distribution.

So far known only from Algeria and Morocco (Gomy et al. 2011). New to Libya and Djibouti.

Elytral humeri not particularly enlarged; inner subhumeral stria present only as a row of several punctures; elytral punctation variable, in most specimens reaching elytral base along fourth elytral interval, punctures often present in all elytral intervals, elytral flanks impunctate; punctures regular and deep, separated by about half to several times their own diameter. Propygidium (Fig. 58) and pygidium as in Exaesiopusgrossipes, but covered with denser punctation. Prosternum: prosternal foveae (Fig. 59) weakly impressed; prosternal process otherwise similar to that of Exaesiopusgrossipes. Disc of mesoventrite (Fig. 60) with scattered shallow punctures; intercoxal disc of metaventrite, lateral disc of metaventrite and metepisternum generally similar to those of Exaesiopushenoni. Intercoxal disc of first abdominal sternite as in Exaesiopusgrossipes. Protibia (Fig. 61) more dilated than that of Exaesiopusgrossipes; on outer margin with two widely-spaced low teeth, topped by large triangular denticle followed by two low rounded denticles imbedded in outer protibial margin; protibial spur inconspicuous (absent?) protibia otherwise similar to that of Exaesiopusgrossipes. Mesotibia (Fig. 62) generally similar to that of Exaesiopusgrossipes. Metatibia (Fig. 63) perhaps most triangularly dilated and thickened of all congeners; outer margin with approximately three widely-spaced tiny denticles; inner margin with a dense row of minuscule rounded denticles; no rows of denticles present between the two rows, surface rugulose-lacunose.

Generally the most punctate species of Exaesiopus, which can be confused only with densely punctate specimens of Exaesiopusgrossipes from N Africa. It clearly differs from them by the punctation of pronotum as well as male genitalia (see also Key to species for details).

Body length: PEL: 2.50–2.75 mm; APW: 1.00–1.10 mm; PPW: 2.00–2.25 mm; EW: 2.125–2.40 mm; EL: 1.50–1.875. Body shape (Fig. 73) as in its congeners, cuticle with greenish metallic tinge; legs, mouthparts and antennae reddish-brown. Antennae as those of Exaesiopusgrossipes; sensory structures of the antenna not examined. Mouthparts: mandibles somewhat more slender than those of Exaesiopusgrossipes; labrum with large antero-median depression, otherwise similar to that of Exaesiopusgrossipes; mentum and rest of the mouthparts likewise. Clypeus (Fig. 74) rectangular, rugose, anterior margin elevated, depressed medially; frontal, supraorbital and postorbital striae (Fig. 74) as in Exaesiopusgrossipes; frons with several irregularly shaped carinate transverse rugae intermingled with numerous tiny rugae; at times transverse rugae obliterated under numerous tiny rugae; eyes flattened, but visible from above. Pronotum as in Exaesiopusgrossipes. Elytra similar to that of Exaesiopusgrossipes; inner subhumeral stria present medially; elytral punctation, however, mostly confined to apical half of elytra, only rarely punctures present on other than fourth elytral interval. Punctation of propygidium (Fig. 75) and pygidium similar to those of Exaesiopusgrossipes, but punctures on propygidium almost confluent. Prosternum (Fig. 76) most similar to that of Exaesiopusglaucus, foveae small but deep; prosternal process asetose. Mesoventrite (Fig. 77) occasionally sparsely and finely punctate, otherwise similar to that of Exaesiopusglaucus; intercoxal disc of metaventrite similar to that of Exaesiopusglaucus; longitudinal depression in female very faint; lateral metaventral stria, rest of lateral disc of metaventrite, metepisternum + fused metepimeron (Fig. 78) most similar to those of Exaesiopusglaucus, but the amber setae distinctly longer and denser. Intercoxal disc of first abdominal sternite most similar to that of Exaesiopusglaucus. Protibia (Fig. 79) similar to that of Exaesiopusglaucus, differing from it chiefly by lower teeth topped by large triangular denticle. Mesotibia and metatibia similar to those of Exaesiopusglaucus; metatibia, however, slightly more thickened and dilated.

Exaesiopusatrovirens is most similar externally to Exaesiopusglaucus, differing from it by longer vestiture on underside of the body, numerous irregular rugae of frons, more thickened and dilated metatibia, larger triangular denticles of protibia, and male genitalia (compare Figs 80–88 with Figs 107–113; see also Key to species for details). From the rest of the congeners it differs chiefly by its greenish metallic hue of the dorsum (other species are not metallic).

Biology.

Found in sand, often under Tamarix.

Distribution.

Known from Turkey, Russia, Armenia, Azerbaijan, Georgia, Kazakhstan, Iran, Afghanistan and Turkmenistan. New to Ukraine and Tajikistan.

Body (Fig. 89) without metallic tinge; legs, mouthparts and antennae light brown; antennal club amber. Antennae as in Exaesiopusgrossipes; sensory structures of the antennal club not examined. Mouthparts: mentum (Fig. 90) glabrous, sub-quadrate, shallowly inwardly arcuate on anterior margin; anterior margin with several rather long setae intermingled with short sparse ramose setae; rest of the mouthparts as in Exaesiopusgrossipes. Clypeus and frons (Fig. 91) similar to those of Exaesiopushenoni. Pronotum almost smooth, only laterally and behind head with vague patches of shallow sparse punctation; otherwise similar to that of Exaesiopushenoni. Elytra: inner subhumeral stria absent; elytral disc entirely smooth. Propygidium and pygidium (Fig. 92) similar to other congeners, but only sparsely punctate, punctures separated by several times their own diameter. Prosternum (Fig. 93): prosternal foveae tiny, almost invisible; prosternal process otherwise similar to that of other congeners. Mesoventrite (Fig. 94) glabrous, about as long as wide; metaventrite smooth; lateral disc of metaventrite and metepisternum similar to those of Exaesiopushenoni. Intercoxal disc of first abdominal sternite similar to that of Exaesiopushenoni. Protibia (Figs 95–96) similar to that of Exaesiopushenoni, but outer margin of teeth topped by large triangular denticles, more similar in size than those of Exaesiopushenoni, furthermore outer part of posterior surface of protibia of Exaesiopuslaevis obscurely variolate, whereas it is glabrous in Exaesiopushenoni. Mesotibia generally similar to that of Exaesiopushenoni, but denticles on outer margin shorter. Metatibia (Fig. 97) likewise generally similar to that of Exaesiopushenoni, but denticles on outer margin more numerous.

This species is most similar to Exaesiopushenoni, from which it differs by almost impunctate pronotum (punctate in Exaesiopushenoni), smooth elytra (punctate in Exaesiopushenoni) and obscurely variolate posterior surface of protibia (glabrous in Exaesiopushenoni). From the rest of Exaesiopus species it differs by the characters given in the Key to species (below).

Biology.

Unknown, possibly similar to the congeners.

Distribution.

Known only from north-extreme tip of Somalia: Guardafoui.

Remarks.

This species is morphologically rather similar to Exaesiopushenoni, which is known also from the neighbouring Djibouti. The discovery of a male of Exaesiopuslaevis would help to elucidate the identities of the two respective species.

This species has been described based on a single specimen collected in Okahandja (Namibia) (Bickhardt 1914: 280). According to the personal information by the curator of ZMHUB B. Jaeger, the specimen was deposited at the Hamburg Museum of Natural History (Germany), which has been destroyed during WWII. The type specimen of this species can thus be considered as lost and hence a Neotype is designated herein.

Body length: PEL: 2.50–2.60 mm; APW: 0.80–1.00 mm; PPW: 1.83–2.00 mm; EW: 2.00–2.18 mm; EL: 1.50–1.60 mm. Body (Fig. 98) similar to the species Exaesiopusatrovirens, with feeble metallic tinge; legs, mouthparts and antennae light brown. Antennae as in Exaesiopusgrossipes. Mouthparts: as in Exaesiopusgrossipes; labrum with median keel-like elevation, surface anterad of it semi-circularly depressed; mentum (Fig. 99) sub-trapezoid, anterior margin without median notch, fringed with several long setae, lateral margins with single row of sparse shorter ramose setae; stipes with four setae; other mouthparts similar to those of Exaesiopusatrovirens. Clypeus (Fig. 100) rectangular, obscurely variolate, anterior margin elevated, formed by two transverse tubercles that can occasionally be connected forming thus a ridge-like structure; clypeus and frons otherwise similar to those of Exaesiopusatrovirens, but without numerous irregular rugae. Pronotum: sides slightly convergent on basal 3/4, strongly convergent on apical ¼; disc with round dense punctation, laterally punctures larger in size and increasingly ellipsoid, occasionally confluent; postero-median part of disc smooth, punctation stops short of lateral pronotal margin leaving a narrow impunctate band; pronotal base with a single row of round punctures; pronotal hypomeron with short amber setae almost invisible from dorsal view; scutellum small, visible. Elytra: humeral elytral stria well impressed on basal fourth; inner subhumeral stria present medially as a short median fragment; elytral punctation confined to apical half of elytra, along elytral suture reaches up to 2/3 of elytral length anteriorly, punctures in most cases do not enter elytral intervals, regular and deep, separated by about their own diameter, punctation does not become denser apically; rest of elytra impunctate. Propygidium and pygidium (Fig. 101) similar to other congeners, with coarse and dense regular punctation. Prosternum (Fig. 102): prosternal foveae well impressed, rather small, but deep; prosternal process slightly concave, otherwise similar to that of other congeners. Mesoventrite (Fig. 103) slightly wider than long, almost smooth; meso-metaventral sutural stria well impressed, undulate; intercoxal disc of metaventrite with longitudinal depression in both sexes, more prominent in male, almost smooth, except for several rows of variously-sized deep punctures along base; lateral metaventral stria, lateral disc of metaventrite and metepisternum similar to those of Exaesiopushenoni. Intercoxal disc of first abdominal sternite as with the rest of congeners. Protibia (Fig. 104) on outer margin with two moderately large triangular teeth, topped by rounded denticle followed by another two lower teeth topped by small round denticle and another tiny denticle entombed in outer protibial margin; setae of outer row regular and short; setae of median row shorter than those of outer row; anterior protibial stria almost complete; protibial groove deep; protibial spur (Fig. 105) distinct but tiny, growing out from apical margin of protibia; outer part of posterior surface of protibia rugulose-lacunose, clearly separated from comparatively narrower glabrous median part; posterior protibial stria complete, terminating in two tiny inner posterior denticles; inner margin of protibia with single row of short lamellate setae. Mesotibia not particularly dilated or thickened, outer margin similar to that of Exaesiopushenoni; posterior mesotibial stria fine, shortened apically; mesotibial spur stout, prominent and long; anterior surface of mesotibia smooth; anterior mesotibial stria shortened apically; claws of last tarsomere almost straight, their length approximately half the length of apical-most mesotarsomere. Metatibia (Fig. 106) slightly more dilated and thickened than mesotibia, but always more slender than that of the rest of the congeners; two rows of denticles on outer margin widely separated permitting for placement of another two denticles between the two rows; claws of apical-most metatarsomere shorter than half its length; otherwise metatibia similar to mesotibia. Male genitalia. Eighth sternite (Figs 107–108) entirely fused medially, apically with a setose velum; apex of eighth sternite with short dense setae. Eighth tergite apically weakly inwardly arcuate; eighth sternite and tergite fused laterally (Fig. 109). Ninth tergite (Fig. 110) on apical margin faintly inwardly arcuate; tenth tergite on apical margin regularly rounded, weakly inwardly arcuate basally. Spiculum gastrale (Figs 110–111) with typical ‘head’ and ‘tail’; aedeagus (Figs 112–113) tube-like, sub-parallel, slightly widening apically; parameres fused along their basal three-fourths, apex of aedeagus with pores; basal piece short, ratio of its length : length of parameres approximately 1:5.

Exaesiopusglaucus is arguably the most distinctive species of the genus differing from all other members by only slightly dilated metatibia (strongly dilated in all other species, compare Fig. 106 with e.g. 97); present and observable protibial spur (very tiny or absent in the rest of species, compare Fig. 105 with e.g. 43). Furthermore, the setae of the pronotal hypomeron are rather short and invisible from dorsal view (in all other species they are protruding from underside of the pronotum and are observable from dorsal view).

Biology.

Found on a beach by the technique of shore-washing as well as on a river bank on deposited debris.

Distribution.

Described from Namibia; newly recorded from the Republic of South Africa.

Remarks.

The placement of this species in Exaesiopus must be regarded as tentative, as it differs from the rest of the members chiefly by only slightly instead of strongly dilated metatibiae. Hypocaccus from the Old World, however, does not contain any species with ciliate pronotal hypomera, and keeping Exaesiopusglaucus in Hypocaccus would make it heterogeneous. Note that it was already Reichardt (1926) who remarked that this species should be, based on its ciliate pronotal hypomeron, moved into the genus Exaesiopus. Thérond, in the 1960’s and 1970’s identified this species as ‘Exaesiopus’, rather than ‘Hypocaccus’ glaucus.

Body length: PEL: 2.125 mm; APW: 0.875 mm; PPW: 1.825 mm; EW: 2.05 mm; EL: 1.55 mm. This species (Fig. 114) is externally very similar to Exaesiopushenoni, differing from it chiefly by its densely punctate pronotum, which is furnished with two round glabrous patches amongst the punctation laterally. The structure of frons (Fig. 115) is also different; whereas Exaesiopushenoni always possesses only two well-defined chevrons on a completely glabrous surface, Exaesiopustherondi has its chevrons beset on all sides with irregular rugae. The punctation of propygidium and pygidium (Fig. 116) is similar to that of Exaesiopushenoni (Fig. 38). The prosternal process (Fig. 117) of Exaesiopustherondi is more setose than that of Exaesiopushenoni; prosternal foveae are absent. Anterior face of profemora (Fig. 117) is covered with dense amber setae in Exaesiopustherondi, whereas only several sparse short setae are present in Exaesiopushenoni. Anterior face of protibia (Fig. 117) is rugulose-lacunose in Exaesiopustherondi while it is glabrous in Exaesiopushenoni. Further differences are found on male genitalia: Eighth sternite (Figs 118–119) is more slender, setae on apex are shorter; eighth sternite and tergite apically more slender (seen from lateral view; compare Figs 48 and 122). The rest of the male genitalia is markedly similar between the two species.

Exaesiopustherondi most resembles the Saharan species Exaesiopushenoni, differing from it by rugulose-lacunose anterior face of protibia (glabrous in Exaesiopushenoni), and the different structure of the frons (Exaesiopushenoni has its frons glabrous with two chevrons whereas Exaesiopustherondi has the chevrons surrounded by tiny rugae).

Biology.

Unknown, found in a stomach of Kentish plover (Charadriusalexandrinus L.).

Distribution.

Known only from Afghanistan: Hamud-i-Sabari.

Remarks.

Although this newly described species does strongly resemble the Saharan species Exaesiopushenoni, and it has furthermore been found in a stomach of a bird, it is unlikely that they are conspecific, given the vast geographic stretch between African Sahara and Afghanistan. If it had been consumed by a Kentish plover in Africa and discovered in its stomach in Afghanistan it would have probably passed through the digestive tract of the bird by the time the bird migrated from the Sahara Desert to Afghanistan and would be beneath recognition at best. Instead, given the perfect shape of the insect, I consider it highly probable that the bird consumed it in Afghanistan and thus this species is an element of the Afghan fauna.

Key to the species of the genus Exaesiopus Reichardt, 1926

1 (2)

Mesotibia only slightly thickened and dilated (Fig. 106); protibial spur distinct (Fig. 105); species from Namibia and the Republic of South Africa

Punctate species (Fig. 114); frons (Fig. 115) except for chevrons also with additional tiny rugae, species from Afghanistan

Exaesiopustherondi sp. n.

8 (3)

Protibia on outer margin with two to three low teeth topped by large triangular or rounded denticles, followed by two to three lower rounded denticles entombed in outer protibial margin (Figs 10, 61, 79).

9 (10)

Elytral punctation mostly confined to apical third to half of elytra, never occupying all elytral intervals; species with feeble to distinct green metallic hue (Fig. 73)

Punctation of pronotum does not reach pronotal margin, leaving antero-median part of pronotum glabrous (Fig. 1); male genitalia: eighth sternite and tergite slightly more slender than in the preceding species; aedeagus on apical half slightly thickened (Figs 17–34), species from the circum-Mediterranean, Canary Islands, S Europe and Iraq

Exaesiopusgrossipes (Marseul, 1855)

Discussion

Exaesiopus is a taxon that is morphologically well adapted to the psammophilous and fossorial way of life by the thickened metafemora as well as dilated pro- and especially metatibiae. A setose underside of the body is common to most obligate psammophiles in Histeridae and serves as further adaptation to life in sand; setae possibly prevent tiny particles of sand entering the body cavities. Although morphologically united by at least one weak synapomorphy (ciliate pronotal hypomeron), which is possibly a parallelism shared by some Hypocaccus spp. from North America, the monophyly of the genus Exaesiopus is likely questionable. The taxonomical uncertainties between (mostly) littoral taxa Hypocaccus, Exaesiopus, Pachylopus, Neopachylopus, Eopachylopus, etc. lie chiefly in the morphological similarities resulting from ecological pressures causing multiple parallelisms and convergences of characters. A future phylogenetic analysis of all littoral Hypocaccus-like taxa should focus on characters in systems putatively independent of the environmental selection pressures; otherwise characters that are prone to homoplasies (e.g. setae, denticles, rugae, trichomes etc.) could continue to obscure true phylogenetic relationships. In the recently published phylogeny of the subfamily by the author (Lackner 2014d), which included mostly the type species of the Saprininae genera, the type species of Exaesiopus was recovered among the members of a large clade of mostly psammophilous taxa whose inter-relationships are unresolved.

Members of Exaesiopus are found in sandy soils or in sand over a vast geographic area rivalling perhaps only the distribution of Xenonychus Wollaston, 1864 (see also Lackner 2012). The distribution of Exaesiopus covers the area from the Canary Islands, circum-Mediterranean, South Europe, Caucasus, Iraq, Somalia, Djibouti, as far east as Afghanistan. Identity of the Somali species Exaesiopuslaevis Thérond, 1964 is uncertain; the species is known from a single female only. Other related genera (sensu Lackner, 2014) e.g. the species-rich and widespread Hypocaccus or Hypocacculus, or monotypic and localized Eopachylopus, Reichardtia etc., are distributed along most of the world beaches, as well as inland sand-systems; their inter-relationships shall be the focus of future phylogenetic studies.

Acknowledgements

Thanks are due to all curators and proprietors of the collections for their help with Exaesiopus specimens. This research received support from the SYNTHESYS Project http://www.synthesys.info/, which is financed by the European Community Research Infrastructure Action under the FP7 Integrating Activities Program as well as by the Internal Grant Agency (IGA n.20124364) Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Czech Republic. Special thanks are due to one anonymous reviewer and the editor for Histeroidea at ZooKeys who provided numerous corrections and suggestions resulting in higher quality of this paper.